With the advancement of electronic technologies, diverse types of image forming apparatuses have been developed, and have become widespread. An image forming apparatus forms an images or text on a recording medium such as, e.g., paper. Examples of an image forming apparatus may include a printer, a copier, a facsimile machine, or a multifunctional peripheral combining some of the functions of afore-mentioned.
The image forming apparatus may employ various methods in forming an image. For example, an image forming method, often referred to as an electrophotography, may generally involve charging of a photoconductive surface, forming a latent image through light exposure of the charged surface, developing the latent image with toner into a visible toner image, transferring the developed toner image to a sheet of paper and then fusing the toner onto the sheet of paper.
The afore-mentioned fusing of the toner onto the sheet of paper is accomplished with the use of a fuser device included in an image forming apparatus employing an electrophotographic method of image forming. The fuser generally achieves the fusing of the image by applying heat and pressure to the recording medium, e.g., the sheet of paper, and thus required a supply of an electrical power of an appropriate level to enable the fuser to produce the heat.
However, the level of available alternating current (AC) power varies depending on the country or region. For example, a voltage of 220 Volts (V) is used as a standard rated voltage in Korea, whereas a voltage of 110V is used as a standard rated voltage in Japan. Further, even when the standard rated voltage were to be fixed, the input voltage may still change or fluctuate depending on the environmental condition under which the voltage is consumed.
In a typical electronic apparatus, a switching mode power supply (SMPS) may be used to convert the input AC voltage into a direct current (DC) voltage of a fixed level. A fuser device of a typical image forming apparatus, however, applies the received input AC voltage to a heating roller without first converting it into a DC voltage. Thus, a change in the input AC voltage may impact the operation of such fuser devices.
When the input AC voltage is greater than a rated voltage, the quantity of heat that is produced by the fuser may become excessively large. While known input power control schemes, e.g., by the use of a known control software, may be able to achieve control over the input voltage to some limited extent, a temperature fluctuation associated with the fuser may nevertheless become excessive, possibly resulting in an overshoot, which may in turn cause the fuser to overheat, and in some cases to fail because of such overheating.
On the other hand, when the input AC voltage is lower than the rated voltage, it may be difficult for the fuser to reach the target temperature, which may adversely impact the image fusing performance of the fuser device. Therefore, control systems for and methods of controlling an effective operation of a fuser device notwithstanding some change in an input AC voltage are desirable.